Ingredients

Method

Preheat the oven to 200°C/400oF/gas mark 6.

Bring to the boil a large saucepan of salted water. Add the leeks and blanch for 3–6 minutes until tender. Remove from the water with a slotted spoon, drain thoroughly and put the leeks into an ovenproof dish. Reserve 200ml (1 cup) of the leek cooking liquid.

Meanwhile, prepare the bechamel sauce. In a saucepan, melt the butter over a medium heat and add the flour. Cook the flour for about 2 minutes until light golden colour. Pour over the milk and reserved leek cooking liquid water and whisk vigorously to combine the flour smoothly.

Bring to a simmer and cook for 8–10 minutes. Remove from the heat and add the cheese.

Pour the sauce over the leeks and season with salt and black pepper. Place the dish in the oven and bake for 5 minutes until caramelized